Hermit crab

The effects of cadmium may be modulated by environmental factors, including salinity and the presence of other compounds. The synergistic inhibition of limb regeneration in the hermit crab Uca pugilator caused by combinations of cadmium and methylmerciiry is only evident in water of high salinity. ... 

Ceriodaphnia reticulata Hermit crab, Clibanarius olivaceous ... 

Ajmalkhan, S., K. Rajendran, and R. Natarajan. 1986. Effect of zinc on zoeal development of the estuarine hermit crab Clibanarius olivaceus (Henderson). Proc. Indian Acad. Sci. 95 515-524. 

LC50 (96-h) static lab bioassay for Crangon septemspinosa (sand shrimp) 0.6 pg/L, Palaemonetes vulgaris pg/L, Paguruslongicarpus (hermit crab) 6 pg/L (Eisler, 1969). 

LC50 (96-h static bioassay) for sand shrimp 4 pg/L, hermit crab 45 pg/L, grass shrimp 15 pg/L (Eisler, 1969), Pteronarcyscalifomica0.10 pg/L (Sanders and Cope, 1968). 

At the other extreme are adaptations to very low concentrations of a particular element. We have already seen mechanisms directed towards the sequestration of iron when it is present in small amounts. The ability to detect extremely small amounts of an element can be a useful adaptation for an animal if that element is important to it. For example, hermit crabs recognize shells suitable for occupation not only by tactile... 

Brooks, W. R., Chemical recognition by hermit crabs of their symbiotic sea anemones and a predatory octopus, Hydrobiologia, 216/217, 291, 1991. 

Brooks, W.R. and Gwaltney, C.L., Protection of symbiotic cnidarians by their hermit crab hosts evidence for mutualism, Symbiosis, 15, 1, 1993. 

A mixture of polyandrocarpidine metabolites 15 3—156 from the ascidian Polyandrocarpa sp. deters feeding by hermit crabs and two species of snails.28 Nitrogenous ascidian compounds that are reported to lack antifeedant effects include patellamide C (Lissochnurn patella),28 and eudistomins G and H.176... 

A third form of symbiosis, in addition to mutualism and parasitism, is commensalism (Latin com = with mensa = table). In commensal relationships, one symbiotic partner benefits from the association and the other is unaffected. Different variants of snch relationships have been described. Inquilinism is a kind of commensalism where the symbiont uses a host for housing, snch as birds hving in the holes of trees. A more indirect dependency exists if a symbiont uses something its host has created before its death. This commensalism is termed metabiosis. A typical metabiont is the hermit crab that uses gastropod shells. In phoresy, the symbiont uses the host for transportation. An example for phoresy is the burdock, a plant with fruits that adhere to fur and are dispersed by the movement of mammals. 

Most amazing was a melon-sized clump of matter that we held in our hands and turned around to examine like an extraplanetary object. In the middle was a starry-eyed hermit crab, peering out from underneath a shell encrusted with a half dozen hitchhiker anemones. Elsewhere on the surface was a pair of thumbnail-sized porcelain crabs Tewes handed me a magnifying glass so I could see their exquisite markings. 

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